OTTAWA -- There are fears Canadian military aircraft operating over Syria could be caught in the middle of a new and potentially explosive dispute between the U.S. and Russia.

Moscow is warning that it will target allied aircraft operating west of the Euphrates River in Syria in retaliation for the U.S. shooting down a Syrian government warplane on Sunday.

American officials say the Syrian jet dropped bombs near U.S.-backed forces fighting the Islamic State of Iraq and the Levant -- a claim the Syrian government and Russia both dispute.

The Canadian military has been flying surveillance aircraft and a refuelling plane over Syria for the past several months as part of its contribution to the U.S.-led anti-ISIL coalition.

National Defence says it is monitoring the situation, but otherwise won't comment on where the planes have been flying in Syria and whether they are in any danger.

The Trudeau government is reviewing possible changes to Canada's mission against ISIS, whose current mandate is set to expire at the end of the month.